Persons who need respiratory support or breathing air supply frequently obtain the breathing gas via a breathing mask that is in contact with the face. Such breathing masks are used in the area of occupational safety or in medical applications. The breathing gas is fed in such a case to the user of the mask either breath by breath, or a gas flow is provided, which is discharged continuously via an expiration valve and continuously flushes the interior space of the mask with fresh breathing gas.
The wearing comfort of a breathing mask, which is pressed onto the mask user's face by means of a strap, is determined by a contact line in the form of a sealing frame between the mask body of the breathing mask and the face of the mask user. To adapt the breathing mask to different face shapes, it is known that masks can be offered in different sizes, namely, “small,”, “medium” and “large.” The individual shape of the face is adapted by a more or less flexible sealing lip. Since the sealing lip must undergo deformation in a relatively large area, it may happen that zones with different pressing pressures will develop on the face.
A sealing frame made of a plastic material for a breathing mask has become known from DE 39 35 890 A1. The sealing frame has a circumferential sealing part, which consists of a special, deformable material. To adapt the sealing part to the shape of the face of the mask user, the material is heated to a relatively low temperature of about 40° C. to 65° C., which does not appear to be too hot to the user of the mask on contact with the skin. The material is selected such that it will harden again at room temperature. During the shaping of the sealing part, the heated and softened material is placed over the face of the mask user and molded corresponding to the contours of the face. The drawback is that a separate heat source must be available.
A breathing mask for positive pressure respiration, in which the sealing frame consists of an inflatable sealing bead, is known from U.S. Pat. No. 4,971,051. A separate hand pump, which must be steadily available for filling in more air, is necessary to inflate the sealing bead.